The related prior art is that of devices for walking, called “mini steppers”, marketed for numerous years by large retailers and specialty stores and essentially described in the patent FR2791266.
They are of the type comprising:                two pedals designed to be alternately actuated by the lower limbs of the user;        a common frame resting on the ground;        a means designed to connect, in an articulated manner, each pedal to the frame;        a means, positioned between each pedal and the frame, designed to oppose a resistance to the pressure exerted on each pedal by of the lower limbs;        a means, positioned between the pedals and the frame, designed to produce a restoring force adapted to bring back up the pedal that is no longer actuated by the corresponding lower limb and well as the aforementioned limb.        
They have the main drawbacks tied to the fact that the means identified above are implemented by mechanical devices (joints, hydraulic dampers, rods, pins, pulleys, . . . ) that have many points of wear and noise disturbances requiring their regular lubrication and the frequent return of the devices for repair, even replacement, as they are not suitable for intensive use.
In addition, they are heavy and bulky and difficult to transport for, for example, use outside the home during weekends or holidays.
For example, a mini stepper has overall dimensions 450×300×340 mm, weighs approximately 6 kg and is only guaranteed 12 months for non-intensive use (10 minutes per day).